The present invention relates to telecommunications in general, and, more particularly, to a technique for using a software-defined transceiver to support wireless telecommunications.
FIG. 1 depicts a schematic diagram of a portion of a typical wireless telecommunications system in the prior art, which system provides wireless telecommunications service to a number of wireless terminals (e.g., wireless terminals 101-1 through 101-3) that are situated within a geographic region. The heart of a typical wireless telecommunications system is Wireless Switching Center (xe2x80x9cWSCxe2x80x9d) 120, which may also be known as a Mobile Switching Center (xe2x80x9cMSCxe2x80x9d) or Mobile Telephone Switching Office (xe2x80x9cMTSOxe2x80x9d). Typically, Wireless Switching Center 120 is connected to a plurality of base stations (e.g., base stations 103-1 through 103-5) that are dispersed throughout the geographic area serviced by the system and to the local and long-distance telephone and data networks (e.g. local-office 130, local-office 138 and toll-office 140). Wireless Switching Center 120 is responsible for, among other things, establishing and maintaining calls between wireless terminals and between a wireless terminal and a wireline terminal (e.g., wireline terminal 150), which is connected to the system via the local and/or long-distance networks.
The geographic region serviced by a wireless telecommunications system is partitioned into a number of spatially distinct areas called xe2x80x9ccells.xe2x80x9d As depicted in FIG. 1, each cell is schematically represented by a hexagon; in practice, however, each cell usually has an irregular shape that depends on the topography of the terrain serviced by the system. Typically, each cell contains a base station, which comprises the radios and antennas that the base station uses to communicate with the wireless terminals in that cell and also comprises the transmission equipment that the base station uses to communicate with Wireless Switching Center 120.
For example, when wireless terminal 101-1 desires to communicate with wireless terminal 101-2, wireless terminal 101-1 transmits the desired information to base station 103-1, which relays the information to Wireless Switching Center 120 over wireline 102-1. Upon receipt of the information, and with the knowledge that it is intended for wireless terminal 101-2, Wireless Switching Center 120 then returns the information back to base station 103-1 over wireline 102-1, which relays the information, via radio, to wireless terminal 101-2.
Wireless terminals 101-1 and 101-2 may, however, operate under different wireless telecommunications standards (e.g., FDMA, TDMA, CDMA, etc.). Such different standards vary in numerous ways, including carrier frequencies, bandwidth, modulation scheme, to name but a few. To enable communication between wireless terminals 101-1 and 101-2 operating under such different standards, base station 103-1 must be able to provide the processing required to support both such telecommunications standards.
One prior art approach for supporting multiple telecommunications standards involves using duplicative hardware. In particular, for such an approach, base station 103-1 uses a first receiver/transmitter pair for communication with wireless terminal 101-1 and a second receive/transmitter pair for communication with wireless terminal 101-2. Such duplicative hardware increases base station cost.
As an alternative to using duplicative hardware, software-defined radios have been used as receivers and transmitters. With software-defined radios, an operator of a wireless telecommunications system can program a processor containing software and execute such software to both receive and transmit radio signals. To support the different telecommunications standards, the operator of the wireless telecommunications system will typically program the software processor with different programs to receive and transmit signals for the different systems employed within the telecommunications system. While more cost effective than using duplicative hardware, using multiple software programs to support different telecommunications disadvantageously requires software modifications whenever telecommunications standards are updated. The updating of numerous software programs can in itself be an expensive maintenance cost of an operating wireless telecommunications system.
While there have been attempts in the prior art to simplify transceiver operation via software-defined devices, such devices have typically been xe2x80x9cstandards specific.xe2x80x9d In other words, such devices include unique programming to support communications for a specific telecommunications standard. A software control logic package capable of handling communications supported by a variety of telecommunications standards would simplify transceiver operation and would be beneficial to the art. The efforts of the prior art notwithstanding, such desired simplification has, until now, remained elusive.
In some embodiments, the present invention provides a wireless telecommunications system that uses a transceiver having a generic architecture. For transceiver operation to be xe2x80x9cgeneric,xe2x80x9d it must be able to handle a plurality of channels associated with each of a variety of telecommunications systems. Such a generic package, which would be installed unmodified at different locations operating under different standards, reduces the hardware costs associated with duplicative hardware and the maintenance requirements of duplicative software packages of the prior art.
Such a transceiver is operable to receive and transmit information-bearing signals over the variety of telecommunications systems and standards without hardware or software modifications thereto.
The present invention advantageously avoids the complexity of the prior art approaches, either hardware or software based. For example, in one embodiment of the present invention, a generic receiving section of a base station will reject channels that are not specifically allocated to the base station. Unlike a typical prior art receiver, there is no need to design or tune the receiver to handle the allocated channels. In other words, the same generic receiving section could be located in another base station and used to handle other channels allocated to the other base station without modification thereto.
An illustrative method in accordance with the present teachings comprises the operations of: receiving uplink analog RF signals at a base station; converting the uplink analog RF signals into IF uplink digital signals in an analog-to-digital converter; converting the IF uplink digital signals into a number of narrow-band uplink channels; and demodulating selected narrow-band uplink channels from the total number of narrow-band uplink channels.